ObjectiveTo compare the effects of saddle, lumbar epidural and caudal blocks on anal sphincter tone using anorectal manometry.MethodsPatients undergoing elective anorectal surgery with regional anaesthesia were divided randomly into three groups and received a saddle (SD), lumbar epidural (LE), or caudal (CD) block. Anorectal manometry was performed before and 30 min after each regional block. The degree of motor blockade of the anal sphincter was compared using the maximal resting pressure (MRP) and the maximal squeezing pressure (MSP).ResultsThe study analysis population consisted of 49 patients (SD group, n = 18; LE group, n = 16; CD group, n = 15). No significant differences were observed in the percentage inhibition of the MRP among the three regional anaesthetic groups. However, percentage inhibition of the MSP was significantly greater in the SD group (83.6 ± 13.7%) compared with the LE group (58.4 ± 19.8%) and the CD group (47.8 ± 16.9%). In all groups, MSP was reduced significantly more than MRP after each regional block.ConclusionsSaddle block was more effective than lumbar epidural or caudal block for depressing anal sphincter tone. No differences were detected between lumbar epidural and caudal blocks.
ObjectiveTo evaluate the anatomical safety margins in relation to thoracic epidural block by analysing magnetic resonance (MR) images.MethodsThis retrospective study identified consecutive patients who underwent MR imaging of the thoracic vertebral spine. The distance from the dura mater to the spinal cord (DTC) was measured at different thoracic intervertebral levels using three different pathways as references: the ‘U’, ‘L’ and ‘M’ lines.ResultsA total of 346 patients provided MR images for analysis. The vertical DTC was the longest at the T5/6 intervertebral level (mean ± SD: 4.22 ± 1.43 mm) and the shortest at the T11/12 intervertebral level (mean ± SD: 2.51 ± 0.87 mm). The DTC was the longest on the ‘L’ line at the T1/2 and T5/6 intervertebral levels and on the ‘U’ line at the T10/11 intervertebral level. The difference in DTC between the ‘U’ and ‘L’ lines was the greatest at the T5/6 intervertebral level.ConclusionDifferences in the DTC were observed among the thoracic intervertebral levels. The variability of the safety margin according to the angle of needle insertion was the largest at the T5/6 intervertebral level.
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